Mussels. They're usually cooked.I think I tried oysters once but I'm not 100% on that. Never had a clam (unless you count those attached to a woman, then I've eaten plenty of those raw) and I had to look up what cherrystones were so never had them either.
What are those black shellfish that are less circular and more elongated? My mom used to talk about collecting them down the shore when she was a kid.